US20190331643A1 - Additive Manufacture of Metal Objects; Inspection and Part Validation - Google Patents

Additive Manufacture of Metal Objects; Inspection and Part Validation Download PDF

Info

Publication number
US20190331643A1
US20190331643A1 US15/962,903 US201815962903A US2019331643A1 US 20190331643 A1 US20190331643 A1 US 20190331643A1 US 201815962903 A US201815962903 A US 201815962903A US 2019331643 A1 US2019331643 A1 US 2019331643A1
Authority
US
United States
Prior art keywords
response signal
emat
acoustic signals
resonance
acoustic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
US15/962,903
Other versions
US10627370B2 (en
Inventor
Adam C. Cobb
Albert J. PARVIN, JR.
Barron J. Bichon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Southwest Research Institute SwRI
Original Assignee
Southwest Research Institute SwRI
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Southwest Research Institute SwRI filed Critical Southwest Research Institute SwRI
Priority to US15/962,903 priority Critical patent/US10627370B2/en
Assigned to SOUTHWEST RESEARCH INSTITUTE reassignment SOUTHWEST RESEARCH INSTITUTE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: COBB, ADAM C., PARVIN, ALBERT J., JR., BICHON, BARRON J.
Publication of US20190331643A1 publication Critical patent/US20190331643A1/en
Application granted granted Critical
Publication of US10627370B2 publication Critical patent/US10627370B2/en
Active legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
    • B23K31/125—Weld quality monitoring
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/11—Analysing solids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/12—Analysing solids by measuring frequency or resonance of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2412—Probes using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/42—Detecting the response signal, e.g. electronic circuits specially adapted therefor by frequency filtering or by tuning to resonant frequency
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/4454—Signal recognition, e.g. specific values or portions, signal events, signatures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/01—Indexing codes associated with the measuring variable
    • G01N2291/011—Velocity or travel time
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/01—Indexing codes associated with the measuring variable
    • G01N2291/015—Attenuation, scattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0258—Structural degradation, e.g. fatigue of composites, ageing of oils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/0289—Internal structure, e.g. defects, grain size, texture
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0422—Shear waves, transverse waves, horizontally polarised waves

Definitions

  • This invention relates to additive manufacturing, and more particularly to a nondestructive test method for inspecting metal objects manufactured by additive manufacturing.
  • additive manufacturing refers to a process of making three-dimensional objects under computer control with material being added together (such as liquid molecules or powder grains being fused together). Unlike material removed from a stock in a machining process, additive manufacturing builds the three-dimensional object by successively adding material layer by layer.
  • the manufactured objects can be of almost any shape or geometry and typically are produced using digital model data from a computer file.
  • additive manufacturing technologies such as stereolithography or fused deposit modeling.
  • 3D printing originally referred to a process that deposits a binder material onto a powder bed with inkjet printer heads, layer by layer. More recently, the term is being used in popular vernacular to encompass a wider variety of additive manufacturing techniques. However, global technical standards use the term “additive manufacturing” in this broader sense, since the goal of additive manufacturing is to achieve mass-production, in contrast to 3D printing for rapid prototyping.
  • Additive manufacturing is an emerging technology that promises a host of improvements compared to conventional manufacturing, such as allowing production of more complex components and reducing manufacturing waste.
  • additive manufacturing is vulnerable to flaws that are unique to the production process. These flaws result in uncertainty in the mechanical properties of components, such as porosity and local material property variations.
  • FIG. 1 illustrates a system for testing additive manufactured (AM) objects in accordance with the invention.
  • FIG. 2 illustrates the operation of the EMAT of FIG. 1 .
  • FIG. 3 illustrates material characteristics that can be evaluated with the method, based on wave velocity.
  • FIG. 4 illustrates an example of a response signal used for velocity measurement.
  • FIG. 5 illustrates a calibration step of the test method.
  • FIG. 6 illustrates the test method in progress for several AM parts.
  • NDE nondestructive evaluation
  • AM additive manufacturing
  • the method is a field-deployable NDE solution that can be used to qualify AM objects based on their microstructural properties.
  • the method focuses on quantifying variations resulting from defects unique to AM objects.
  • the basis of the method is to perform accurate measurements of acoustic parameters. These parameters are then used to qualify the material microstructure to determine if the object can be certified for use.
  • FIG. 1 illustrates an inspection station 12 for inspecting a number of AM parts 10 in accordance with the invention.
  • the objects to be inspected are referred to herein as “parts”, that term is used in its most general sense to refer to any discrete three-dimensional object.
  • Inspection station 12 implements the computer process described herein.
  • a control unit 16 has a user interface, and has processing hardware and software for implementing the tasks described herein. Control unit 16 receives measurement signals, and controls other hardware of measurement station 12 , as well as provides a user interface for measurement station 12 and for reporting results of testing.
  • An electromagnetic acoustic transducer (EMAT) 13 generates and transmits long-duration acoustic signals into a part 10 being inspected.
  • the transmitted signals have a duration that exceeds the time it takes for the sound to reverberate in the material.
  • a transmitter 14 energizes EMAT 13 with single-frequency sinusoidal signals.
  • a high precision receiver 15 such as a superheterodyne receiver, quantifies the signal energy at the transmit frequency, and delivers measurement signals to control unit 16 .
  • EMAT 13 is activated by sending a single-frequency long-duration signal to it.
  • long-duration is meant that the signal transmitted into the part 10 has many cycles of the same sine wave that all have the same wavelength. The goal is to send so many cycles that the acoustic waveform has time to bounce back and forth between the boundaries of the part being tested. As a result, early parts of the acoustic wave interact with later parts.
  • FIG. 2 illustrates the operation of EMAT 13 .
  • EMAT 13 When the test object 10 is close to the EMAT 13 , ultrasonic waves are generated in the object through the interaction of two magnetic fields. Depending on the configuration of the EMAT 13 , shear waves or longitudinal waves can be generated.
  • the long-duration signals overlap with themselves as they reverberate in the material of part 10 . If the wavelength of sound generated is an integer multiple of the material thickness, it will constructively interfere with itself and produce a strong signal. By sweeping in frequency, it is possible to measure which wavelengths establish these resonance states.
  • Two acoustic measurements of interest are acoustic attenuation of the signal amplitude and wave velocity.
  • the time it takes for the sound to decay from the resonance amplitude is directly related to the attenuation.
  • wave velocity with a known specimen thickness (d)
  • the wave velocity (c) is computed using the n th resonance peak f n by the following relationship:
  • Measured wave velocities are acoustic shear (c 2 ) and longitudinal (c 2 ) wave velocities. For isotropic materials, these wave velocities can be used to compute many different material property values.
  • FIG. 3 illustrates material property values that can be computed from wave velocity, where p is the density of the material. These include Shear Modulus, Young's Modulus, and Poisson's Ratio. Material properties such as these are important for characterizing AM objects. For example, Young's modulus (elastic modulus) measures the resistance of a material to elastic deformation under load. It has been shown that both grain size and porosity affect the elastic moduli of a material, thus giving an indication of material build quality. For direct metal laser sintering (a type of AM), both the grain structure and consistency of the part (i.e. lack of porosity) are key characteristics to the overall quality of the AM object.
  • Young's modulus elastic modulus
  • Attenuation the other acoustic parameter of interest, is the reduction in signal amplitude partially due to scattering.
  • the attenuation time can be measured for either shear or longitudinal waves.
  • Acoustic attenuation can be used to qualitatively detect the presence of porosity in the manufactured material. Porosity is a commonly occurring defect in AM objects, and affects various mechanical properties, including material strength and fatigue life. Experimentation indicates that porosity increases the acoustic attenuation from sound scattering in the material. Thus, by monitoring attenuation, it is possible to detect porosity and inform the manufacturer that the object has potentially undesirable characteristics.
  • FIG. 4 illustrates an example of a response signal used for velocity measurement, and the ability to resolve two different shear wave speeds. More specifically, FIG. 4 is a resonance spectrum acquired on a 5.85 mm thick aluminum plate using a shear-wave EMAT 13 . Given a nominal shear wave speed of 3.15 mm per microsecond and the plate thickness, there should be a resonance peak approximately every 270 kHz. As shown, there are regularly spaced pairs of peaks in the resonance spectrum. The pairs of peaks are produced because this material supports two different shear wave speeds depending on the polarization of the wave with respect to the manufacturing rolling direction.
  • the resonance peaks for the two different wave speeds can be distinguished, and based on these peaks, the two shear wave speeds are measured as 3.1345 mm per microsecond and 3.1530 mm per microsecond. From this example, it is clear that the method described herein can discriminate between two different speeds less than 0.6% apart.
  • FIGS. 1, 5 and 6 illustrate a method of testing objects made by applied manufacturing, in accordance with the invention.
  • an inspection station 12 is set up, comprising an EMAT sensor 13 and other instrumentation. As explained above, the inspection station 12 is operable to perform high resolution, resonance-based acoustic measurements.
  • FIG. 5 illustrates how inspection station 12 is calibrated.
  • a known-good calibration piece 51 has been produced with the same AM process as the objects 10 to be tested.
  • the calibration piece 51 has the same geometry as the objects 10 , and has their desired material properties.
  • the process of FIG. 5 is used to baseline the pass criteria of the inspection station 12 .
  • FIG. 6 illustrates the inspection process for a number of AM objects 10 .
  • the object 10 currently being tested has a defect 61 .
  • Control unit 16 may be programmed to display or otherwise output the results of testing for each object 10 . If an object does not pass inspection, control unit 10 may display or sound an alert so that the object 10 can be removed from production stock. A more sophisticated graphical user interface can be used for alerts and reporting, as well as to configure and control EMAT 13 .

Landscapes

  • Physics & Mathematics (AREA)
  • Immunology (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Mechanical Engineering (AREA)
  • Electromagnetism (AREA)
  • Signal Processing (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

Methods of testing the material of a metal object made by additive manufacturing. An electromagnetic acoustic transducer (EMAT) is used to transmit long duration acoustic signals into the object, and to receive response signals representing resonance of acoustic waves within the material. At least one resonance peak is identified and used to determine attenuation and/or wave velocity. These values can then be used to determine material properties, such as porosity, Shear Modulus, Young's Modulus, or Poisson's Ratio.

Description

    TECHNICAL FIELD OF THE INVENTION
  • This invention relates to additive manufacturing, and more particularly to a nondestructive test method for inspecting metal objects manufactured by additive manufacturing.
    • BACKGROUND OF THE INVENTION
  • “Additive manufacturing” refers to a process of making three-dimensional objects under computer control with material being added together (such as liquid molecules or powder grains being fused together). Unlike material removed from a stock in a machining process, additive manufacturing builds the three-dimensional object by successively adding material layer by layer. The manufactured objects can be of almost any shape or geometry and typically are produced using digital model data from a computer file. There are different additive manufacturing technologies, such as stereolithography or fused deposit modeling.
  • The term “3D printing” originally referred to a process that deposits a binder material onto a powder bed with inkjet printer heads, layer by layer. More recently, the term is being used in popular vernacular to encompass a wider variety of additive manufacturing techniques. However, global technical standards use the term “additive manufacturing” in this broader sense, since the goal of additive manufacturing is to achieve mass-production, in contrast to 3D printing for rapid prototyping.
  • Additive manufacturing is an emerging technology that promises a host of improvements compared to conventional manufacturing, such as allowing production of more complex components and reducing manufacturing waste. However, additive manufacturing is vulnerable to flaws that are unique to the production process. These flaws result in uncertainty in the mechanical properties of components, such as porosity and local material property variations.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:
  • FIG. 1 illustrates a system for testing additive manufactured (AM) objects in accordance with the invention.
  • FIG. 2 illustrates the operation of the EMAT of FIG. 1.
  • FIG. 3 illustrates material characteristics that can be evaluated with the method, based on wave velocity.
  • FIG. 4 illustrates an example of a response signal used for velocity measurement.
  • FIG. 5 illustrates a calibration step of the test method.
  • FIG. 6 illustrates the test method in progress for several AM parts.
    •  DETAILED DESCRIPTION OF THE INVENTION
  • The following description is directed to a nondestructive evaluation (NDE) method for detecting and quantifying flaws in metal objects made with additive manufacturing (AM). The method allows parts and other objects to be qualified and certified for their intended use quickly and inexpensively.
  • More specifically, and as explained below, the method is a field-deployable NDE solution that can be used to qualify AM objects based on their microstructural properties. The method focuses on quantifying variations resulting from defects unique to AM objects. The basis of the method is to perform accurate measurements of acoustic parameters. These parameters are then used to qualify the material microstructure to determine if the object can be certified for use.
  • FIG. 1 illustrates an inspection station 12 for inspecting a number of AM parts 10 in accordance with the invention. Although the objects to be inspected are referred to herein as “parts”, that term is used in its most general sense to refer to any discrete three-dimensional object.
  • Inspection station 12 implements the computer process described herein. A control unit 16 has a user interface, and has processing hardware and software for implementing the tasks described herein. Control unit 16 receives measurement signals, and controls other hardware of measurement station 12, as well as provides a user interface for measurement station 12 and for reporting results of testing.
  • An electromagnetic acoustic transducer (EMAT) 13 generates and transmits long-duration acoustic signals into a part 10 being inspected. The transmitted signals have a duration that exceeds the time it takes for the sound to reverberate in the material.
  • In addition to the EMAT 13, a transmitter 14 energizes EMAT 13 with single-frequency sinusoidal signals. A high precision receiver 15, such as a superheterodyne receiver, quantifies the signal energy at the transmit frequency, and delivers measurement signals to control unit 16.
  • In operation, EMAT 13 is activated by sending a single-frequency long-duration signal to it. By “long-duration” is meant that the signal transmitted into the part 10 has many cycles of the same sine wave that all have the same wavelength. The goal is to send so many cycles that the acoustic waveform has time to bounce back and forth between the boundaries of the part being tested. As a result, early parts of the acoustic wave interact with later parts.
  • FIG. 2 illustrates the operation of EMAT 13. When the test object 10 is close to the EMAT 13, ultrasonic waves are generated in the object through the interaction of two magnetic fields. Depending on the configuration of the EMAT 13, shear waves or longitudinal waves can be generated.
  • The long-duration signals overlap with themselves as they reverberate in the material of part 10. If the wavelength of sound generated is an integer multiple of the material thickness, it will constructively interfere with itself and produce a strong signal. By sweeping in frequency, it is possible to measure which wavelengths establish these resonance states.
  • Two acoustic measurements of interest are acoustic attenuation of the signal amplitude and wave velocity. For attenuation, the time it takes for the sound to decay from the resonance amplitude is directly related to the attenuation. For wave velocity, with a known specimen thickness (d), the wave velocity (c) is computed using the nth resonance peak fn by the following relationship:
  • c = 2 df n n .
  • Measured wave velocities are acoustic shear (c2) and longitudinal (c2) wave velocities. For isotropic materials, these wave velocities can be used to compute many different material property values.
  • FIG. 3 illustrates material property values that can be computed from wave velocity, where p is the density of the material. These include Shear Modulus, Young's Modulus, and Poisson's Ratio. Material properties such as these are important for characterizing AM objects. For example, Young's modulus (elastic modulus) measures the resistance of a material to elastic deformation under load. It has been shown that both grain size and porosity affect the elastic moduli of a material, thus giving an indication of material build quality. For direct metal laser sintering (a type of AM), both the grain structure and consistency of the part (i.e. lack of porosity) are key characteristics to the overall quality of the AM object.
  • Attenuation, the other acoustic parameter of interest, is the reduction in signal amplitude partially due to scattering. The attenuation time can be measured for either shear or longitudinal waves. Acoustic attenuation can be used to qualitatively detect the presence of porosity in the manufactured material. Porosity is a commonly occurring defect in AM objects, and affects various mechanical properties, including material strength and fatigue life. Experimentation indicates that porosity increases the acoustic attenuation from sound scattering in the material. Thus, by monitoring attenuation, it is possible to detect porosity and inform the manufacturer that the object has potentially undesirable characteristics.
  • FIG. 4 illustrates an example of a response signal used for velocity measurement, and the ability to resolve two different shear wave speeds. More specifically, FIG. 4 is a resonance spectrum acquired on a 5.85 mm thick aluminum plate using a shear-wave EMAT 13. Given a nominal shear wave speed of 3.15 mm per microsecond and the plate thickness, there should be a resonance peak approximately every 270 kHz. As shown, there are regularly spaced pairs of peaks in the resonance spectrum. The pairs of peaks are produced because this material supports two different shear wave speeds depending on the polarization of the wave with respect to the manufacturing rolling direction. The resonance peaks for the two different wave speeds can be distinguished, and based on these peaks, the two shear wave speeds are measured as 3.1345 mm per microsecond and 3.1530 mm per microsecond. From this example, it is clear that the method described herein can discriminate between two different speeds less than 0.6% apart.
  • FIGS. 1, 5 and 6 illustrate a method of testing objects made by applied manufacturing, in accordance with the invention.
  • Referring again to FIG. 1, an inspection station 12 is set up, comprising an EMAT sensor 13 and other instrumentation. As explained above, the inspection station 12 is operable to perform high resolution, resonance-based acoustic measurements.
  • FIG. 5 illustrates how inspection station 12 is calibrated. A known-good calibration piece 51 has been produced with the same AM process as the objects 10 to be tested. The calibration piece 51 has the same geometry as the objects 10, and has their desired material properties. The process of FIG. 5 is used to baseline the pass criteria of the inspection station 12.
  • FIG. 6 illustrates the inspection process for a number of AM objects 10. The object 10 currently being tested has a defect 61.
  • If an object 10 is good, it will fall within the calibrated pass criteria. If the object 10 is bad (has a defect) 61, that part will not be within the pass criteria and will be rejected.
  • Control unit 16 may be programmed to display or otherwise output the results of testing for each object 10. If an object does not pass inspection, control unit 10 may display or sound an alert so that the object 10 can be removed from production stock. A more sophisticated graphical user interface can be used for alerts and reporting, as well as to configure and control EMAT 13.

Claims (10)

What is claimed is:
1. A method of testing the material of a metal object made by additive manufacturing, comprising:
using an electromagnetic acoustic transducer (EMAT) to transmit transmitted acoustic signals into the object;
wherein the transmitted acoustic signals have a duration that exceeds the time it takes for them to reverberate within the material of the object;
using the EMAT to receive a response signal representing resonance of acoustic waves within the material;
identifying at least one resonance peak in the response signal;
measuring the time for the response signal to decay from the resonance peak;
determining an attenuation value based on the measuring step; and
evaluating porosity of the material, based on the attenuation value.
2. The method of claim 1, wherein the step of using the EMAT to transmit is performed sweeping through transmit frequencies.
3. The method of claim 1, wherein the acoustic signals are shear waves.
4. The method of claim 1, wherein the acoustic signals are longitudinal waves.
5. A method of testing the material of a metal object made by additive manufacturing, comprising:
using an electromagnetic acoustic transducer (EMAT) to transmit transmitted acoustic signals into the object;
wherein the transmitted acoustic signals have a duration that exceeds the time it takes for them to reverberate within the material of the object;
using the EMAT to receive a response signal representing resonance of acoustic waves within the material;
identifying at least one resonance peak in the response signal;
measuring a wave velocity of the response signal, based on the material thickness and the resonance peak frequency; and
using the wave velocity to calculate one of more of the following properties of the material: Shear Modulus, Young's Modulus, or Poisson's Ratio.
6. The method of claim 5, wherein the step of using the EMAT to transmit is performed sweeping through transmit frequencies.
7. The method of claim 5, wherein the acoustic signals are shear waves.
8. The method of claim 5, wherein the acoustic signals are longitudinal waves.
9. An inspection station for testing the material of a metal object made by additive manufacturing, comprising:
an electromagnetic acoustic transducer (EMAT) operable to transmit transmitted acoustic signals into the object, and to receive a response signal representing resonance of acoustic waves within the material;
wherein the transmitted acoustic signals have a duration that exceeds the time it takes for them to reverberate within the material of the object;
a control unit operable to perform the following tasks: to identify at least one resonance peak in the response signal, measure a wave velocity of the response signal, based on the material thickness and the resonance peak frequency; and to use the wave velocity to calculate one of more of the following properties of the material: Shear Modulus, Young's Modulus, or Poisson's Ratio.
10. An inspection station for testing the material of a metal object made by additive manufacturing, comprising:
an electromagnetic acoustic transducer (EMAT) operable to transmit transmitted acoustic signals into the object, and to receive a response signal representing resonance of acoustic waves within the material;
wherein the transmitted acoustic signals have a duration that exceeds the time it takes for them to reverberate within the material of the object;
a control unit operable to perform the following tasks: to identify at least one resonance peak in the response signal, measure the time for the response signal to decay from the resonance peak, determine an attenuation value based on the measuring step, and evaluate porosity of the material, based on the attenuation value.
US15/962,903 2018-04-25 2018-04-25 Additive manufacture of metal objects; inspection and part validation Active 2038-07-29 US10627370B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US15/962,903 US10627370B2 (en) 2018-04-25 2018-04-25 Additive manufacture of metal objects; inspection and part validation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15/962,903 US10627370B2 (en) 2018-04-25 2018-04-25 Additive manufacture of metal objects; inspection and part validation

Publications (2)

Publication Number Publication Date
US20190331643A1 true US20190331643A1 (en) 2019-10-31
US10627370B2 US10627370B2 (en) 2020-04-21

Family

ID=68291094

Family Applications (1)

Application Number Title Priority Date Filing Date
US15/962,903 Active 2038-07-29 US10627370B2 (en) 2018-04-25 2018-04-25 Additive manufacture of metal objects; inspection and part validation

Country Status (1)

Country Link
US (1) US10627370B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3845336A1 (en) * 2020-01-02 2021-07-07 The Boeing Company Systems and methods for inspecting additively manufactured components

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746121A (en) * 1969-10-24 1973-07-17 L Niklas Ultrasound pulse echo method and apparatus for determining acoustic velocity of materials
US5811682A (en) * 1995-12-13 1998-09-22 Ebara Corporation Electromagnetic acoustic transducer EMAT and inspection system with EMAR
US6008887A (en) * 1998-03-20 1999-12-28 Lasson Technologies, Inc. Single beam laser surface velocity and displacement measurement apparatus
US6109108A (en) * 1995-12-13 2000-08-29 Ebara Corporation Electromagnetic acoustic transducer EMAT and inspection system with EMAR
US6257048B1 (en) * 1998-06-22 2001-07-10 The United States Of America As Represented By The United States Department Of Energy Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors
US6382029B1 (en) * 2000-03-07 2002-05-07 The United States Of America As Represented By The Secretary Of Commerce Apparatus and method for utilizing electromagnetic acoustic transducers to non-destructively analyze in-service conductive materials
US6534964B1 (en) * 2000-09-22 2003-03-18 International Business Machines Corporation Apparatus and method for determining stiffness properties of an anisotropic electronic substrate using scanning acoustic microscopy
US20030167137A1 (en) * 2002-03-04 2003-09-04 Toshihiro Ohtani Method and apparatus for diagnosing damages of conductive materials
US20040085550A1 (en) * 2002-11-05 2004-05-06 Kawasaki Steel Corporation Material thickness measurement method and apparatus
US20070140310A1 (en) * 2003-01-20 2007-06-21 Rolton Peter E Identification of materials by non destructive testing
US20090044627A1 (en) * 2007-08-15 2009-02-19 Steven Kenneth Brady Capacitive electromagnetic acoustic inspection apparatus
US20110167914A1 (en) * 2008-06-27 2011-07-14 Jeffrey Earle Sutherland Integrated multi-sensor non-destructive testing
US20140318251A1 (en) * 2011-12-19 2014-10-30 Snecma Method for measuring elastic properties using ultrasound

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746121A (en) * 1969-10-24 1973-07-17 L Niklas Ultrasound pulse echo method and apparatus for determining acoustic velocity of materials
US5811682A (en) * 1995-12-13 1998-09-22 Ebara Corporation Electromagnetic acoustic transducer EMAT and inspection system with EMAR
US6109108A (en) * 1995-12-13 2000-08-29 Ebara Corporation Electromagnetic acoustic transducer EMAT and inspection system with EMAR
US6008887A (en) * 1998-03-20 1999-12-28 Lasson Technologies, Inc. Single beam laser surface velocity and displacement measurement apparatus
US6257048B1 (en) * 1998-06-22 2001-07-10 The United States Of America As Represented By The United States Department Of Energy Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors
US6382029B1 (en) * 2000-03-07 2002-05-07 The United States Of America As Represented By The Secretary Of Commerce Apparatus and method for utilizing electromagnetic acoustic transducers to non-destructively analyze in-service conductive materials
US6534964B1 (en) * 2000-09-22 2003-03-18 International Business Machines Corporation Apparatus and method for determining stiffness properties of an anisotropic electronic substrate using scanning acoustic microscopy
US20030167137A1 (en) * 2002-03-04 2003-09-04 Toshihiro Ohtani Method and apparatus for diagnosing damages of conductive materials
US20040085550A1 (en) * 2002-11-05 2004-05-06 Kawasaki Steel Corporation Material thickness measurement method and apparatus
US20070140310A1 (en) * 2003-01-20 2007-06-21 Rolton Peter E Identification of materials by non destructive testing
US20090044627A1 (en) * 2007-08-15 2009-02-19 Steven Kenneth Brady Capacitive electromagnetic acoustic inspection apparatus
US20110167914A1 (en) * 2008-06-27 2011-07-14 Jeffrey Earle Sutherland Integrated multi-sensor non-destructive testing
US20140318251A1 (en) * 2011-12-19 2014-10-30 Snecma Method for measuring elastic properties using ultrasound

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3845336A1 (en) * 2020-01-02 2021-07-07 The Boeing Company Systems and methods for inspecting additively manufactured components

Also Published As

Publication number Publication date
US10627370B2 (en) 2020-04-21

Similar Documents

Publication Publication Date Title
Wronkowicz et al. Assessment of uncertainty in damage evaluation by ultrasonic testing of composite structures
Zhang et al. Effect of roughness on imaging and sizing rough crack-like defects using ultrasonic arrays
US20210349058A1 (en) Ultrasonic system and method for evaluating a material
US11754529B2 (en) System and method for evaluating defects in a material
US12066405B2 (en) System and method for real-time degree of cure evaluation in a material
US12055519B2 (en) System and method for real-time visualization of foreign objects within a material
CN115540790A (en) High-precision ultrasonic thickness measurement method and device
CN103097884B (en) For measuring the method and apparatus in the orientation of defect present in mechanical part
EP2573556B1 (en) Device and method for the non-destructive inspection of a test object of great material thickness by means of ultrasound
US10627370B2 (en) Additive manufacture of metal objects; inspection and part validation
CN112432998B (en) Ultrasonic nondestructive testing method for bonding defect of rubber plate with acoustic cavity structure
CN203117167U (en) Ultrasonic detector for road steel bridge
Scalerandi et al. Discrimination between cracks and recrystallization in steel using nonlinear techniques
CN203069556U (en) Ultrasonic detection device for highway steel bridge
CN101147058B (en) Determining average mechanical properties of constituent particles of a sample of material using ultrasound
Prevorovsky et al. NDT in additive manufacturing of metals
Sun et al. Damage identification in thick steel beam based on guided ultrasonic waves
Bazulin et al. Testing samples made of polymer composite materials using ultrasonic antenna arrays
Simonetti et al. Ultrasonic interferometry for the measurement of shear velocity and attenuation in viscoelastic solids
JP2003130851A (en) Elastic parameter measuring device for material surface and coating layer
Quan et al. Near surface residual stress detection of metallic materials using the high order ultrasonic nonlinear coefficient
RU2196982C2 (en) Procedure determining physical and mechanical characteristics and composition of polymer composite materials in structures by ultrasonic method
RU2274856C1 (en) Method of determining degree of polymerization of composite materials
RU2231054C1 (en) Method of determination of degree of polymerization of composite materials
Kachanov et al. The use of complex-modulated signals to increase the accuracy of measurements of the velocity of ultrasound in concrete

Legal Events

Date Code Title Description
FEPP Fee payment procedure

Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

AS Assignment

Owner name: SOUTHWEST RESEARCH INSTITUTE, TEXAS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:COBB, ADAM C.;PARVIN, ALBERT J., JR.;BICHON, BARRON J.;SIGNING DATES FROM 20180502 TO 20180503;REEL/FRAME:045780/0458

FEPP Fee payment procedure

Free format text: ENTITY STATUS SET TO SMALL (ORIGINAL EVENT CODE: SMAL); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

STPP Information on status: patent application and granting procedure in general

Free format text: NON FINAL ACTION MAILED

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YR, SMALL ENTITY (ORIGINAL EVENT CODE: M2551); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

Year of fee payment: 4